A conventional interior permanent-magnet electric motor has the following problems:
1. The electric motor has a large cogging torque and a large electromagnetic torque ripple;
2. A back electromotive force has a high harmonic content, especially a high low-frequency harmonic content;
3. The electric motor has a large quadrature axis inductance and a low power factor of the electric motor, which causes a large controller capacity and a high cost;
4. The electric motor has a low efficiency;
5. The electric motor generates great noise and vibration.
In this regard, provided is an improved solution where a center of an inner circular arc end-face of a stator tooth and a center of an outer circular arc of a rotor are both deviated from a center of a rotor bore. This solution solves the first and second problems, but still has defects. Specifically, eccentricity of a stator inner circular arc will reduce an area of a stator slot and decrease the number of turns of the electric motor, thus affecting an efficiency of the electric motor; additionally, an increase in tooth harmonics intensifies radial vibration, thereby aggravating electromagnetic vibration and noise.